In recent years, magnetic random access memories (MRAMs) utilizing a tunneling magneto resistive (TMR) effect have been developed. Magneto resistive elements including magnetic tunnel junctions (MTJs) are used in the magnetic random access memories, and such magneto resistive elements have large magnetic resistance change ratios.
In spin injection writing currently under studying, a magneto resistive element structure utilizing perpendicular magnetization films is more preferable to utilizing in-plane magnetization films in terms of reduction in size and lowering electric current.
In a magneto resistive element using perpendicular magnetization films, a nonmagnetic layer that is used as a tunneling barrier film is sandwiched at both surfaces by amorphous interface magnetic layers. The amorphous interface magnetic layers are crystallized through heat treatment in order to achieve a large TMR ratio.
However, boron atoms contained in the interface magnetic layers may not be dissociated sufficiently in the heat treatment, making it difficult to sufficiently crystallize the interface magnetic layers.